Iron or Rust? A Meta-Analysis on Blood Donor Iron Supplementation
Stephen Vamvakas, MD, PhD, a master of meta-analysis, used to quip that performing meta-analyses means never having to do your own study! Meta-analyses combine similar studies to increase statistical power of conclusions. The Cochrane group recently analyzed blood donor iron stores and replacement.
The science of donor iron balance is "iron-clad;" specifically, repeatedly removing 200 mg of iron with each donation depletes iron stores and administering pharmacological iron restores it. Despite this, most blood collection programs do not actively replace donor iron. The meta-analysis identified 30 clinical trials that included over 4,700 participants, representing the best controlled randomized studies on blood donor iron status and various methods of iron replacement to better inform the UK's national blood policy.
They chose the most rigorous studies, in terms of randomized clinical trial design, to identify risks and benefits of donor iron replacement. Their conclusions should speak loudly to those pushing donors to donate more frequently. Specifically, because higher donation frequency, along with donor gender and interval since last donation, resulted in higher risk of iron deficiency. Iron replacement dramatically decreased the risk of deferral at the time of the next donation and, furthermore, decreased the risk of depleted iron stores at the next donation.
This is consistent with findings of the FABC-funded clinical trial performed at Memorial Blood Centers and Mississippi Valley Regional Blood Center, which will be presented at the 2014 AABB Annual Meeting in October. We targeted fixed site donors with low hemoglobin levels and observed that 85 percent had low ferritin levels. The vast majority improved ferritin levels following a 112-day deferral and 100 days of Fe Gluconate (iron) therapy.
Due to side effects that occurred in 29 percent of those on iron replacement, leading many to abandon therapy, the meta-analysis authors recommend targeting those donors at highest risk for iron deficiency (especially female or younger repeat donors) for replacement therapy to balance the risk of side effects with benefits - similar to my own recommendations in the March Transfusion commentary titled, "Iron Man Pentathlon." The high rate of ferritin depletion we and others observed in regular donors might indicate the importance of screening for low ferritin among frequent donors, even with acceptable hemoglobin levels. Alternatively, widespread iron depletion in this population may obviate the need to test ferritin and suggest that we should simply offer iron replacement therapy to all donors giving two or more times per year. In short, we have little excuse to ignore a growing preponderance of data supporting either limiting the number or frequency of red cell donations or replacing the lost iron via supplementation.
Jed Gorlin, MD, MBA, Vice President, Medical & Rgulatory Affairs, Innovative Blood Resources; firstname.lastname@example.org